Experimental and modeled chlorine solubilities in aluminosilicate melts at 1 to 7000 bars and 700 to 1250 C: Applications to magmas of Augustine Volcano, Alaska

Abstract

Hydrothermal experiments were conducted at ca. 1 to 7000 bars and 700 to 1250 °C in 121 rhyolitic to basaltic systems to determine Cl solubility in silicate melts, i.e., the maximum Cl concentration in melts that are saturated in a hydrosaline liquid with or without an aqueous or aqueous-carbonic vapor. The Cl concentration of melts increases with the Cl contents of the fluid unless the melt coexists with vapor plus hydrosaline liquid at fixed pressure and temperature; this phase assemblage buffers the Cl content of each phase with increasing Cl in the system. The Cl content of fluid(s)-saturated melts is independent of the CO2 concentration of the saline liquid ± vapor with up to 21 wt% CO2 in the fluid(s). The experiments show that Cl dissolution in aluminosilicate melts increases with temperature and pressure. Chlorine solubility is also a function of melt composition; it increases with the molar ([Al1/2+Ca1/2+Mg1/2+Na]/Si) of the melt.